Cameras are inherently angular measurement devices, so that they create an image of their surroundings by focusing the solid angle of energy falling onto a camera lens onto an imaging sensor. This imaging sensor is generally a continuous two-dimensional matrix of individual sensing photodiodes or other photon to electron conversion devices, also known as picture elements, or “pixels”. When an array of pixels is positioned behind a lens, each pixel is effectively illuminated by its incrementally small angular share of the energy being collected and focused by the lens. This incrementally small angular share is also known as the instantaneous field of view (IFOV) of each pixel. In non-distorted camera/lens systems, the IFOV is taken to be equal throughout the system, and conversely, distorted optical systems have a non-uniform IFOV across a sensor area of the imaging sensor. All of the IFOVs taken together constitute a camera's field of view, or FOV. Generally, for modern cameras, the FOV of the camera can have a different value for those pixels in the horizontal and vertical directions, as well as in the diagonal direction. The horizontal FOV is also known as the HFOV, and likewise, the vertical and diagonal FOVs are respectively known as the VFOV and DFOV. Generally, the HFOV is larger than the VFOV, and in all cases, the DFOV is the largest FOV of all within a camera system since it represents the FOV of the diagonal of the normally two-dimensional rectangular imaging sensor. When considering the aperture requirements of a camera system, it is customary to project angular rays from the plane of an entrance pupil of the lens/lens system into the environment. This can be done for each of the HFOV, VFOV and DFOV of the lens, and in doing so, it describes the solid angle subtended by the camera/lens system. This solid angle can be used to further determine what the aperture requirements are, or other optical system elements, as well as to determine what the camera system can actually “see”.
When installing camera and sensor systems onto outdoor lighting fixtures, it is advantageous to house these cameras within an external housing in order to reliably and robustly facilitate handling, as well as cosmetic and environmental issues. It is also sometimes desirable to position the cameras of these systems behind a glass transparent window (or the like) for environmental protection as well as for cosmetic reasons. As with all optical systems, alignment of the cameras relative to their surroundings are an important part of their use. This is normally done by utilizing some sort of a simple rotational mechanism which causes the bore sight axis (or central axis) of the camera lens to swivel about some fixed point within this mechanism. This is disadvantageous, however, since doing so will cause the camera lens and its projected FOV to swing through an arc generated by the bore sight axis of the camera lens as it passes through the mechanism pivot point. The larger the rotational requirement for the camera, the longer the arc length that the camera bore sight will trace, and, correspondingly, the larger the aperture of any protective windows in the housing need to be in order to accommodate all rotational aspects of the movement of the camera mechanism and its FOV requirements.